Dynamo construction.



NoA 863,40. n A PATENTED AUGWlS, X907. H. LEITNER. DYNAMO CONSTRUCTION.

L APPLIGATION FILED JUNE 17 1905.

HENRY LEITNER, or

MAYBUEY, WOKING, ENGLAND.

DYNAM CONSTRUCTION.

Application nea im 17,1905. serial No. 265,773.

Specification o f Letters Patent.

Patented Aug. 13, 1907.

To all whom it may concern:

Bc it known that I, HENRY LEITNER, a subject of the King of Great Britain, residing at Maybury, Woking, Surrey, England, have invented new and useful Improvemcnts in Dynamo Construction, of which the following is a specification.

The object of the .presentinvention is mainly to provide a dynamo which in conjunction with a battery of accumulatore is adapted 'to the precise requirements l0 of train lighting, the motive power for the dynamo being derived from the revolution of any axle of the moving train.

The most successful devices of this kind depend for their regulation and for counter-acting the effects of varying spoed upon a small subsidiary dynamo adapted to control the fields of the main dynamo.

The present invention has the advantage of securing all the effects of the control obtainable from a subsidiary dynamo without the constructional additions involved therei n, while having the further advantage of greatly tion of the main dyn-.uno and for its maximum output. It also corrects for any ill effects such as sparking duc to the distortion of the field. v

The invention is applicable to machines of the shunt wound type with two, four, or more poles, but for the Sake of simplicity it will be here described in reference only to a two pole machine.

In carrying out the invention in practice we employ in the case of an ordinaiy two pole shunt Wound machine, in addition lto the ordinary two brushes for providing the current, two additional brushes 'arranged at an angle with thorn, these two brushes providing current which may be termed subsidi-.u'y current. The ordinary two brushes of the machine from which the useful current for charging a battery of accumulators` lighting lamps, or other purposes is taken, are arranged with arj'rreferably considerable lead. The subsidiary brushes touching the com- 40 mutator dialuctrically opposite to each other are arranged betwccnthc two ordinary brushes and a line with the line joining the centers of the pole pieces and this is an angle of advance in the direction of rotation. The amount of subsidiary current or subsidiary E. M. F. which -thc subsidiary brushes furnish depends within limits on their angular distance in the direction of rotation from thc said line joining the centers of the pole pieces. The subsidiary brushes above referred to are connected in between the principal brushes of the machine and its shunt field-winding in such a way that when the ma- 35 chine commencesto rotate and excites, theE. M. F, from the subsidiary brushes assists in building up the reducing the speed required for the full excita- `and then opposes the tendency of current to field, but when a certain moderate speed of rotation has been reached it acts a'gainst the ordinary brushes of the machine thereby tending to diminish the current fiowing through the field-windings and this tendency in creases as the speed of rotation increases, the effect being to progressively weaken the field as the speed of driving increases and so keep theoutput of the machine practically of the speed at which it is driven. The adjustment and the point at which the effect of the E. M. F. of the subsidiary brushes changes from assisting to build up the field to weakening it depends upon their angular distance from the line joining the centers of the pole pieces in the direction of rotation. Instead of employing the opposing E. M. F. of the subsidiary brushes to dam back the current tending to fiow through the fieldwindings we may take an opposing current from the subsidiary brushes round a separate opposing fieldwinding and thereby weaken the field as the speed of driving increases.

Iii order that the nature oi the invention may be the more fully understood we refer to the. accompanying sheet of drawings in which l Figure l illustrates the principle of the invention applied to anl ordinary shunt-wound machine. Fig,

.2 illustrates the invention applied to a similar machine the fields magnets of which are provided with a special coil or Winding round which the current obtained from the additional or subsidiary brushes is taken. Fig. 3 shows the invention applied to the case of 'a separately excited machine the arrangements being such that it can be effectively driven in either direction.

In these figures a represents the commutator of a two polo shunt-wound machine of which b and b1 are the two poles of the field magnet.

c and c1 are the ordinary brushes of the machine plying current to the conductors l, Z1 to the battery of aceumulators which it is ldesired the dynamo should charge. d, d1 are the subsidiary brushes arranged to press 011 the commutator a opposite to one which are taken another and arranged preferably as shown in a plane bei v tween the plane in which the ordinary brushes c, el are fixed and the plane or line x-y bisecting the polepicces b, b1

w is the ordinary shunt field-winding of the field magnet.

w1 Fig. 2 is the speeial'winding round which the current from the subsidiary brushes d, dl is taken.l

Though the parts and windings are shown diagrammatically it will be understood that when the machine is designed "to give a constant output indcpendentlyof the speed at wh1ch it is driven, the counter E. M. F. provided b the subsidiary brushes d and d1 first assists flow in the inFig. l. in the field field winding w, in the arrangement shown Similarly the current which tends to flow Sup- Y constant Within wide limits independently y 4 brosses c, ci, as shown iu the drawing, the following series of events taires placez-When the machine is slowly rotated and just commences to excite, the poiarity ofthe subsidiary brushes d, dl which should be regarded 'the brushes oi an independent controlling dynamo is' such that the 1li. F. is added tothat oi the ordinary brushes thereby increasing the initial current tiowing in the ielcl\vinciii1g it'. As the speed oi rotation on load increases, however, the keffective iields oi the poles et the lield magnets advance in the direction ot rotation owing to armature reaction, and the 'polarity oi the subsidiary brushes Z and di is gradually r sed, their E. M. F. accordine'ly tirs-,t sinking to zero and then opposing the current iiowing in the held-winding 'it'. The greater the speed ot rotation thenceiorward, the greater counter E. M. F. that is produced by trie subsidiary brushes d, d* owing to the angle between them and the poles of the field inilueneing the armature winnings they represent and the output oi the machine is in this way kept practically constantor suitable to train requirements ind ep'endently ofthe speed at which the armature is driven,

The operation oi the arrangement shown in Fig. 2 is entirely similar and equivalent-;-wheu the armature commences to rotate in the direction oi the arrow the two subsidiary brushes d and d tirst furnish a current to the winding il;l which assists the magneiizaing effect on the field magnets produced by the current flowing in the ordinary iieid winding w. As the speed o rotation increases, however7 and the effective polarity acting;- upon thc i nected to the subsidiary brushes advances in the direction ot rotation, the current in the winding 1lil iirst sinks to zero and'then reverses. its effect'thenceorth tends to neutralize the magnetic effect produced by the ordinary winding w, the demagnet-iziner current iiowing in the winding iol increasing with the speed of driving und thus keeping the output oi the machine constant.

The arrangement shown diagraniinatically in F ig. 3 illustrates the application oi the invention to the case ot a separately excited dynamo, its adoption enabling the machine to be effectively driven in either direction and io generate. isetul current without the employment oi reversing mrchanism. or the like. in this iigfuref c, and c are the main brushes the machine as beiore. d and d are the subsidiary brushes arranged in this case on tin,` iinefcy. 'w3 lw3 are the separately excited fieldwindings energized from the battery of accumulators 1) through the conductors l2, Z3 and'li. 102, w'- are fic-idwindi so connected tothe battery but. joined also to the subsidiary brushes d, di in the manner shown. andi1 being as before the main current lends of the machine. l

vWhen the speed at which the dyn-arno is driven 1s small the current from the battery o Hows through both ndingw1 Fig. Z connected to the subsidiary brushes d i so, windings oi the armature which are con windings w3, w3 and wg, 102 the arrangements being such that both strengthen the iield, but as the speed increases the counter E. M. F. of the brushes d, d more and more opposes the accumulator current in wl, 1112 and-ulti! mately evenyoverpowers it. In this way the iield is suitably'wealrened as the driving-speed increases and the current trom the brushes c, c1 is maintained coniparatively constant over a wide range ot' speed. It it is desired to make the machine reversible independent oi separate excitation, ZL and ll are connected to l and l or vice versa according to the direction oi' rotation by suitable change-over mechanism as shown iu F ig. 'l.

It will be understoodvthat the device shown in Fig. 3 may be varied by disconnecting the windings i 1, wl

from vwi and tu and connecting` them together so ns to correspond with the arrangement illustrated in lI lg. 2.

it will be obvious that the output oi the machine as arranged in accordance with two oi the iigures may lilrewise be varied by varying the position oi the subsidiary brushes d, di, and it is preferable though not absolutely indispensable that the angular distance between the main and subsidiary brushes should be kept constant by mounting them upon the same rocker or by other suitable means. it will also be obvious that *further regulation may be obtained by closingr the subsidiary brushes d, dl through any suitable (variablel resistance.

It will be plain that the arrangements above described have the effect of providing a dynamo the peculiarities of which are specially suited to the requirements oi train lighting, i. c., it excites with ease and rnpidity at low speeds and very quickly reaches its maximum output while at more than average speeds the output can be vmade to decrease to a more or less permanent minimum. I

IIavinf,r now particularly described and ascertahwd the nature ot' our said invention and in what manner the same is to he performed, we declare that what we claim is:.- Y

l. in :i dynamo, tin` combination vwith the electro held magnets. arnuitui'c and main iiui brushes, of u pair oi' lixed subsidiary brushes connected with u winding oi' the lield magnets, the 4subsidiary bi'usbesbeing so loeutcd :ind connected that nl u lou speed ot' the dynamo they :idd to the foi-ce of the iield Iiiuenets und ni n high speed of thc dynamo they lessen the fori-c of the field magnets, subsiuntialiy :is destrihed.

2. in a dynamo, thel combination-with the electro iield magnets, armature and inuin line brushes, of a shunt ot.

the main line through u windingr of the held magnets und subsidiary brushes also connected with a winding' of the iield magnets. said subsidiary brushes beine; so located that when the dynamo is running ai low speed the current from the said subsidiary brushes adds its force to that of thc .said shunt circuit. and when the dynamovis running;- ut a high rate ol' speed opposes the force of the said shunt cirn cuit substantially as described,

3. in u dynamo. thecombinntion with the electro field magnets. armature and main line brushes, oi :i shunt f|;om the. main line through a windingl of the field magnets, :ind u pair otsnbsidiury brushes connected with the shunt circuit. the disposition of thesuid subsidiary brushes heini',f such that when the dynamo is running ai n low speed. the cui-rent ot` the subsidiary brushes increases the current in the shunt circuit, :ind when the dynamo is running; :it :i hic-h speed it decreases the current in the shunt circuit, substantially as described.

HENRY LIHTNER.

Witnesses Joinr ifu'suiunn.

C. G. RunnunN. 

